In 1804 Thomas Jefferson sent thirty-three men to walk off the edge of the known map and find out whether America went all the way across. They came back two years later having lost one man, and the reason the rest lived is written in the journals in a word no dietitian uses: fat. The Corps of Discovery left St Louis in May, hauling a keelboat up the Missouri against the current, by rope, through mud to the waist. Nobody knew what was out there. The maps gave out at the Mandan villages. Beyond that was rumour: mountains that might be a day's walk across, rivers that might run to the Pacific, and animals the size of carts that nobody back east believed in. The men ate like no men have eaten since. Nine pounds of meat a day each, when it could be got. Four deer for the party, or a buffalo, every single day. Clark wrote that they consumed an immensity of meat. And by the autumn of 1805, on the high plains, they had learned the thing the plains people had always known. The buffalo in October carries inches of yellow fat down its back, and the men stripped it off and ate it before they touched the lean. They roasted marrow bones in the embers and sucked them like sweets. Charbonneau stuffed buffalo gut with meat and kidney fat and Lewis, a man who did not hand out praise, called it one of the great dishes of the frontier. They rendered bear grease into kegs and carried it over the Rockies like gold. Then came the winter on the Pacific. Fort Clatsop, rain for a hundred days, and the only game was elk, lean as rope after the mountains. The men lived on it and the journals turn dark: boils, bowel trouble, men laid flat with nothing left in them. The meat was plentiful. It was the fat that had gone. In January a whale washed up on the shore. Lewis sent a party through the surf and over a headland to buy its blubber from the Clatsop people, and when it came back he wrote that providence had been kinder to them than to Jonah, since it had sent the whale to be eaten rather than the reverse. The men came back to life on it. They crossed the Divide, found the river, saw the ocean, and walked home. One grave in 8,000 miles, three months in, a sergeant with a burst appendix. No scurvy in two years without a vegetable. The greatest expedition in American history ran on buffalo fat, bear oil, marrow and whale blubber, and its captains knew exactly what was keeping their men on their feet. Send the same thirty-three men out today with oats, lean turkey and a bag of lentils, and the only thing that reaches Oregon is the paperwork.

5 years on a statin buys you 3.2 days. That is the median. Measured across the trials, in the journal, by people who wanted a bigger number. 5 years of a pill before breakfast. 5 years of aching stairs. 5 years of a repeat prescription that renews itself. 3.2 days. A long weekend, delivered at the very end, when you are least able to use it. 100 people, 5 years, and 1 of them is spared a heart attack. The other 99 paid the same price for nothing. 2 of the 100 pick up diabetes on the way. 10 damage a muscle. Deaths prevented across the whole 100: none that the trials could find. The industry read those numbers and priced them at $125 billion for one brand. The guideline read them and lowered the bar until 8 million Britons qualified. Your doctor read them and told you it was just to be safe. Nobody in that chain gains 3.2 days. They gain the 5 years.

Every one of these was settled science in 1955. Taught in the medical schools, printed in the journals, and defended by the best men in the profession. - A lobotomy for a woman who had not been herself since the baby came. The operation had taken the Nobel Prize in 1949 and tens of thousands had been carried out in America alone. - X-raying the chests of healthy babies to shrink a thymus gland that was exactly the size it was meant to be. - Keeping premature infants in high oxygen for weeks, which was blinding thousands of them, and was blinding the most of them in the very best hospitals. - An oestrogen tablet for pregnant women, still going out on prescription two years after a controlled trial found it did nothing at all. - Mercury in the teething powder, on sale in British chemists, poisoning babies for forty years under the name pink disease. - Six weeks flat on your back after a heart attack, no sitting up, no walking to the lavatory, while the clots formed in your legs. - Tonsils out as a matter of routine, at rates that varied by district rather than by illness. - Doctors in white coats fronting cigarette advertisements, and reassuring pregnant women that a cigarette settled the nerves. Not one of those was quackery. Every one was the consensus, issued by the qualified to the obedient. Settled science, as of this morning: - Cholesterol in your food is irrelevant. The number in your blood is critical. - Butter is evidence of harm and industrially refined seed oil is heart healthy. - Obesity is a chronic disease requiring lifelong medication, now offered to children from the age of twelve. - Depression responds to a drug whose original explanation the profession has since disowned. - Sunlight is a carcinogen, and the vitamin your skin makes from it comes in a capsule. - A statin is appropriate for a well person who has a nine in ten chance of being perfectly fine without it. - Red meat causes cancer, at a level of risk nobody will state in absolute numbers. Taught, audited, paid for and defended. The men who wrote the first list were exactly as certain as the men writing yours, and every one of them died respected.

Things your government is content for you to buy today, without a word: - Vodka, from a fridge, at eight in the morning - Twenty cigarettes, with the photograph of the lung on the packet - A vape in bubblegum flavour, from a shop that opened last Tuesday - A tattoo off a man called Spider, in his garage - A skydive, signed for on a clipboard - A sunbed session, unsupervised, by the minute - Paracetamol, which takes about 200 deaths a year in this country Things it will prosecute a farmer for selling you: - Raw milk Banned outright in Scotland. Legal in England, from the farm gate only, from 140 approved dairies out of 8,000, with a warning printed on the bottle. Cheese made from the identical milk is on sale everywhere, in Scotland included, at fourteen quid a kilo. The raw milk is a public health emergency. The raw cheese is a gift idea. The difference is not the bacteria. It is that one of them has a factory, a lorry and a wholesaler, and the other is a farmer handing a bottle to a woman he knows by name. Nobody has ever needed a licence to sell a doughnut.

The advice tells you to go out in the sun with bare skin and no sunscreen, and it tells you to be indoors, covered, at the exact same hour. Instruction one: most people can make the vitamin D they need from short periods of summer sunlight, forearms or legs uncovered, no sunscreen, because sunscreen blocks the wavelength that makes it. Instruction two, from the same health authorities: cover up whenever the ultraviolet index reaches 3. Shade at midday, sleeves, hat, factor 30 or higher. The wavelength that makes vitamin D is UVB, and UVB is what the index measures. It only reaches 3 when UVB is arriving in useful amounts, which in Britain is roughly eleven to three in summer. The only window in which instruction one is possible is the window instruction two forbids. Outside it there is no vitamin D to be had at all. Inside it you are told to stand in the shade. You are being asked to live in a doorway. How many minutes satisfy both? Nobody will say. Not the dermatology bodies, not the cancer charities, not the health services. Thirty years of this and there is no number anywhere, because a number would be a testable claim. What there is instead is a capsule, recommended through the darker months and year round for anyone who does not get outside much, which is now most of the country. And routine testing is not recommended. The advice removes the source, sells you a replacement, and declines to measure whether it worked. You are descended from people who reaped, fished and marched bare-backed in full sun for four thousand years, and not one of them had a number to hit. Go outside. Roll your sleeves up. Stay out until you have had enough and go in before you burn, which is what every human being managed unaided until about 1980. It is the sun. You were built in it.

LDL is the most slandered molecule in medicine, and the defence of it has been almost as wrong as the attack. Every cell you own has cholesterol built into its membrane, and LDL is how it gets there. Testosterone is made from cholesterol. So is oestrogen, progesterone, cortisol and aldosterone. There is no second route. Vitamin D is made from cholesterol sitting in your skin waiting for sunlight. Bile is made from cholesterol, and without bile you absorb no fat, and no vitamin A, D, E or K. LDL is the delivery vehicle for vitamin E, CoQ10 and the carotenoids, none of which swim through blood on their own. It binds bacterial endotoxin and carries it out of circulation, which makes it part of your immune system. People who arrive in hospital with sepsis and low LDL do worse than people who arrive with high. In people over sixty, higher LDL tracks with the same or lower all-cause mortality across the large majority of cohorts anybody has troubled to look at. Your liver makes most of your cholesterol itself, because it will not leave a supply this important to whatever you decided to have for lunch. Nearly every nucleated cell in your body can build it from scratch. Nothing your body builds its own factories for is a poison. So the particle is not the villain. But something is happening in those arteries, and calling LDL harmless and walking off is the same error wearing the other coat. An LDL particle is a vehicle carrying cargo, and vehicles can be damaged. It can be oxidised, and what oxidises is the polyunsaturated fat packed inside it, which is why the particle takes on the character of the oil you have been cooking in. It can be glycated, sugar-coated, from a lifetime swimming through high blood glucose. It can be kept in circulation far longer than it should be, and the longer it circulates the more of both of those things happen to it. An intact particle goes into the artery wall, does its work, and comes back out. Nothing touches it. A damaged one is taken up by a different receptor entirely, one with no off switch, so the macrophage keeps swallowing until it is too full of fat to move. That immobilised cell is what plaque is built from. The number on your printout is a count of vehicles on the road. It says nothing whatever about the condition any of them are in. Fifty years counting the delivery vans, and nobody once opened the back doors.